diff --git a/src/legacy/core_plugins/kibana/public/dashboard/dashboard_app_controller.tsx b/src/legacy/core_plugins/kibana/public/dashboard/dashboard_app_controller.tsx
index 7972c7603d31113..b5a6db912bdf07d 100644
--- a/src/legacy/core_plugins/kibana/public/dashboard/dashboard_app_controller.tsx
+++ b/src/legacy/core_plugins/kibana/public/dashboard/dashboard_app_controller.tsx
@@ -120,10 +120,6 @@ export class DashboardAppController {
     new FilterStateManager(globalState, getAppState, filterManager);
     const queryFilter = filterManager;
 
-    function getUnhashableStates(): State[] {
-      return [getAppState(), globalState].filter(Boolean);
-    }
-
     let lastReloadRequestTime = 0;
 
     const dash = ($scope.dash = $route.current.locals.dash);
@@ -751,7 +747,7 @@ export class DashboardAppController {
         anchorElement,
         allowEmbed: true,
         allowShortUrl: !dashboardConfig.getHideWriteControls(),
-        shareableUrl: unhashUrl(window.location.href, getUnhashableStates()),
+        shareableUrl: unhashUrl(window.location.href),
         objectId: dash.id,
         objectType: 'dashboard',
         sharingData: {
diff --git a/src/legacy/core_plugins/kibana/public/dashboard/dashboard_state.test.ts b/src/legacy/core_plugins/kibana/public/dashboard/dashboard_state.test.ts
index c236ac7843c0389..b0adcb409b03cd8 100644
--- a/src/legacy/core_plugins/kibana/public/dashboard/dashboard_state.test.ts
+++ b/src/legacy/core_plugins/kibana/public/dashboard/dashboard_state.test.ts
@@ -18,7 +18,7 @@
  */
 
 import './np_core.test.mocks';
-
+import 'ui/state_management/state_storage/mock';
 import { DashboardStateManager } from './dashboard_state_manager';
 import { getAppStateMock, getSavedDashboardMock } from './__tests__';
 import { AppStateClass } from './legacy_imports';
diff --git a/src/legacy/core_plugins/kibana/public/discover/angular/discover.js b/src/legacy/core_plugins/kibana/public/discover/angular/discover.js
index 7af7ee235a166bc..7abb7166aa902a4 100644
--- a/src/legacy/core_plugins/kibana/public/discover/angular/discover.js
+++ b/src/legacy/core_plugins/kibana/public/discover/angular/discover.js
@@ -42,7 +42,6 @@ import {
   getRequestInspectorStats,
   getResponseInspectorStats,
   getServices,
-  getUnhashableStatesProvider,
   hasSearchStategyForIndexPattern,
   intervalOptions,
   isDefaultTypeIndexPattern,
@@ -195,10 +194,8 @@ function discoverController(
   globalState,
 ) {
   const responseHandler = vislibSeriesResponseHandlerProvider().handler;
-  const getUnhashableStates = Private(getUnhashableStatesProvider);
   const filterStateManager = new FilterStateManager(globalState, getAppState, filterManager);
 
-
   const inspectorAdapters = {
     requests: new RequestAdapter()
   };
@@ -333,7 +330,7 @@ function discoverController(
           anchorElement,
           allowEmbed: false,
           allowShortUrl: uiCapabilities.discover.createShortUrl,
-          shareableUrl: unhashUrl(window.location.href, getUnhashableStates()),
+          shareableUrl: unhashUrl(window.location.href),
           objectId: savedSearch.id,
           objectType: 'search',
           sharingData: {
diff --git a/src/legacy/core_plugins/kibana/public/discover/kibana_services.ts b/src/legacy/core_plugins/kibana/public/discover/kibana_services.ts
index 497427136f415a5..0d9dab96d612089 100644
--- a/src/legacy/core_plugins/kibana/public/discover/kibana_services.ts
+++ b/src/legacy/core_plugins/kibana/public/discover/kibana_services.ts
@@ -74,8 +74,6 @@ export { subscribeWithScope } from 'ui/utils/subscribe_with_scope';
 // @ts-ignore
 export { timezoneProvider } from 'ui/vis/lib/timezone';
 // @ts-ignore
-export { getUnhashableStatesProvider } from 'ui/state_management/state_hashing';
-// @ts-ignore
 export { tabifyAggResponse } from 'ui/agg_response/tabify';
 // @ts-ignore
 export { vislibSeriesResponseHandlerProvider } from 'ui/vis/response_handlers/vislib';
diff --git a/src/legacy/core_plugins/kibana/public/visualize/editor/editor.js b/src/legacy/core_plugins/kibana/public/visualize/editor/editor.js
index 5410289bfc2d73b..2cf258481074191 100644
--- a/src/legacy/core_plugins/kibana/public/visualize/editor/editor.js
+++ b/src/legacy/core_plugins/kibana/public/visualize/editor/editor.js
@@ -39,7 +39,6 @@ import {
   getServices,
   angular,
   absoluteToParsedUrl,
-  getUnhashableStatesProvider,
   KibanaParsedUrl,
   migrateLegacyQuery,
   SavedObjectSaveModal,
@@ -166,7 +165,6 @@ function VisEditor(
   localStorage,
 ) {
   const queryFilter = Private(FilterBarQueryFilterProvider);
-  const getUnhashableStates = Private(getUnhashableStatesProvider);
 
   // Retrieve the resolved SavedVis instance.
   const savedVis = $route.current.locals.savedVis;
@@ -250,7 +248,7 @@ function VisEditor(
         anchorElement,
         allowEmbed: true,
         allowShortUrl: capabilities.visualize.createShortUrl,
-        shareableUrl: unhashUrl(window.location.href, getUnhashableStates()),
+        shareableUrl: unhashUrl(window.location.href),
         objectId: savedVis.id,
         objectType: 'visualization',
         sharingData: {
diff --git a/src/legacy/core_plugins/kibana/public/visualize/kibana_services.ts b/src/legacy/core_plugins/kibana/public/visualize/kibana_services.ts
index 612f0ba0f077be1..6477d1941c205df 100644
--- a/src/legacy/core_plugins/kibana/public/visualize/kibana_services.ts
+++ b/src/legacy/core_plugins/kibana/public/visualize/kibana_services.ts
@@ -96,8 +96,6 @@ export { getFromSavedObject } from 'ui/index_patterns';
 export { PersistedState } from 'ui/persisted_state';
 // @ts-ignore
 export { VisEditorTypesRegistryProvider } from 'ui/registry/vis_editor_types';
-// @ts-ignore
-export { getUnhashableStatesProvider } from 'ui/state_management/state_hashing';
 export { showSaveModal } from 'ui/saved_objects/show_saved_object_save_modal';
 export { stateMonitorFactory } from 'ui/state_management/state_monitor_factory';
 export { absoluteToParsedUrl } from 'ui/url/absolute_to_parsed_url';
diff --git a/src/legacy/core_plugins/state_session_storage_redirect/public/index.js b/src/legacy/core_plugins/state_session_storage_redirect/public/index.js
index f64237000ae4161..1aa7bce2af69967 100644
--- a/src/legacy/core_plugins/state_session_storage_redirect/public/index.js
+++ b/src/legacy/core_plugins/state_session_storage_redirect/public/index.js
@@ -20,6 +20,7 @@
 import chrome from 'ui/chrome';
 import { hashUrl } from 'ui/state_management/state_hashing';
 import uiRoutes from 'ui/routes';
+import { fatalError } from 'ui/notify';
 
 uiRoutes.enable();
 uiRoutes
@@ -27,11 +28,14 @@ uiRoutes
     resolve: {
       url: function (AppState, globalState, $window) {
         const redirectUrl = chrome.getInjected('redirectUrl');
+        try {
+          const hashedUrl = hashUrl(redirectUrl);
+          const url = chrome.addBasePath(hashedUrl);
 
-        const hashedUrl = hashUrl([new AppState(), globalState], redirectUrl);
-        const url = chrome.addBasePath(hashedUrl);
-
-        $window.location = url;
+          $window.location = url;
+        } catch (e) {
+          fatalError(e);
+        }
       }
     }
   });
diff --git a/src/legacy/ui/public/chrome/api/sub_url_hooks.js b/src/legacy/ui/public/chrome/api/sub_url_hooks.js
index 142f11e029b3567..e38a1f4b19e56ac 100644
--- a/src/legacy/ui/public/chrome/api/sub_url_hooks.js
+++ b/src/legacy/ui/public/chrome/api/sub_url_hooks.js
@@ -20,18 +20,16 @@
 import url from 'url';
 
 import {
-  getUnhashableStatesProvider,
   unhashUrl,
 } from '../../state_management/state_hashing';
 
 export function registerSubUrlHooks(angularModule, internals) {
   angularModule.run(($rootScope, Private, $location) => {
-    const getUnhashableStates = Private(getUnhashableStatesProvider);
     const subUrlRouteFilter = Private(SubUrlRouteFilterProvider);
 
     function updateSubUrls() {
       const urlWithHashes = window.location.href;
-      const urlWithStates = unhashUrl(urlWithHashes, getUnhashableStates());
+      const urlWithStates = unhashUrl(urlWithHashes);
       internals.trackPossibleSubUrl(urlWithStates);
     }
 
diff --git a/src/legacy/ui/public/state_management/__tests__/state.js b/src/legacy/ui/public/state_management/__tests__/state.js
index cbeb5e3650a1632..0848604889870a1 100644
--- a/src/legacy/ui/public/state_management/__tests__/state.js
+++ b/src/legacy/ui/public/state_management/__tests__/state.js
@@ -25,13 +25,11 @@ import '../../private';
 import { toastNotifications } from '../../notify';
 import * as FatalErrorNS from '../../notify/fatal_error';
 import { StateProvider } from '../state';
-import {
-  unhashQueryString,
-} from '../state_hashing';
 import {
   createStateHash,
   isStateHash,
-} from '../state_storage';
+  unhashQuery
+} from '../state_hashing';
 import { HashedItemStore } from '../state_storage/hashed_item_store';
 import { StubBrowserStorage } from 'test_utils/stub_browser_storage';
 import { EventsProvider } from '../../events';
@@ -60,9 +58,7 @@ describe('State Management', () => {
         const hashedItemStore = new HashedItemStore(store);
         const state = new State(param, initial, hashedItemStore);
 
-        const getUnhashedSearch = state => {
-          return unhashQueryString($location.search(), [ state ]);
-        };
+        const getUnhashedSearch = () => unhashQuery($location.search());
 
         return { store, hashedItemStore, state, getUnhashedSearch };
       };
diff --git a/src/legacy/ui/public/state_management/state.js b/src/legacy/ui/public/state_management/state.js
index 8d55a6929a617a8..ca57252ba3e725c 100644
--- a/src/legacy/ui/public/state_management/state.js
+++ b/src/legacy/ui/public/state_management/state.js
@@ -37,10 +37,12 @@ import { createLegacyClass } from '../utils/legacy_class';
 import { callEach } from '../utils/function';
 
 import {
-  createStateHash,
   HashedItemStoreSingleton,
-  isStateHash,
 } from './state_storage';
+import {
+  createStateHash,
+  isStateHash
+} from './state_hashing';
 
 export function StateProvider(Private, $rootScope, $location, stateManagementConfig, config, kbnUrl, $injector) {
   const Events = Private(EventsProvider);
@@ -293,9 +295,7 @@ export function StateProvider(Private, $rootScope, $location, stateManagementCon
 
     // We need to strip out Angular-specific properties.
     const json = angular.toJson(state);
-    const hash = createStateHash(json, hash => {
-      return this._hashedItemStore.getItem(hash);
-    });
+    const hash = createStateHash(json);
     const isItemSet = this._hashedItemStore.setItem(hash, json);
 
     if (isItemSet) {
diff --git a/src/legacy/ui/public/state_management/state_hashing/__tests__/hash_url.js b/src/legacy/ui/public/state_management/state_hashing/__tests__/hash_url.js
deleted file mode 100644
index 1d5b88a22d9c618..000000000000000
--- a/src/legacy/ui/public/state_management/state_hashing/__tests__/hash_url.js
+++ /dev/null
@@ -1,158 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import expect from '@kbn/expect';
-import ngMock from 'ng_mock';
-import sinon from 'sinon';
-import { parse as parseUrl } from 'url';
-
-import { StateProvider } from '../../state';
-import { hashUrl } from '..';
-
-describe('hashUrl', function () {
-  let State;
-
-  beforeEach(ngMock.module('kibana'));
-
-  beforeEach(ngMock.inject((Private, config) => {
-    State = Private(StateProvider);
-    sinon.stub(config, 'get').withArgs('state:storeInSessionStorage').returns(true);
-  }));
-
-  describe('throws error', () => {
-    it('if states parameter is null', () => {
-      expect(() => {
-        hashUrl(null, '');
-      }).to.throwError();
-    });
-
-    it('if states parameter is empty array', () => {
-      expect(() => {
-        hashUrl([], '');
-      }).to.throwError();
-    });
-  });
-
-  describe('does nothing', () => {
-    let states;
-    beforeEach(() => {
-      states = [new State('testParam')];
-    });
-    it('if url is empty', () => {
-      const url = '';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if just a host and port', () => {
-      const url = 'https://localhost:5601';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if just a path', () => {
-      const url = 'https://localhost:5601/app/kibana';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if just a path and query', () => {
-      const url = 'https://localhost:5601/app/kibana?foo=bar';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if empty hash with query', () => {
-      const url = 'https://localhost:5601/app/kibana?foo=bar#';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if query parameter matches and there is no hash', () => {
-      const url = 'https://localhost:5601/app/kibana?testParam=(yes:!t)';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it(`if query parameter matches and it's before the hash`, () => {
-      const url = 'https://localhost:5601/app/kibana?testParam=(yes:!t)';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if empty hash without query', () => {
-      const url = 'https://localhost:5601/app/kibana#';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if hash is just a path', () => {
-      const url = 'https://localhost:5601/app/kibana#/discover';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-
-    it('if hash does not have matching query string vals', () => {
-      const url = 'https://localhost:5601/app/kibana#/discover?foo=bar';
-      expect(hashUrl(states, url)).to.be(url);
-    });
-  });
-
-  describe('replaces querystring value with hash', () => {
-    const getAppQuery = (url) => {
-      const parsedUrl = parseUrl(url);
-      const parsedAppUrl = parseUrl(parsedUrl.hash.slice(1), true);
-
-      return parsedAppUrl.query;
-    };
-
-    it('if using a single State', () => {
-      const stateParamKey = 'testParam';
-      const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey}=(yes:!t)`;
-      const mockHashedItemStore = {
-        getItem: () => null,
-        setItem: sinon.stub().returns(true)
-      };
-      const state = new State(stateParamKey, {}, mockHashedItemStore);
-
-      const actualUrl = hashUrl([state], url);
-
-      expect(mockHashedItemStore.setItem.calledOnce).to.be(true);
-
-      const appQuery = getAppQuery(actualUrl);
-
-      const hashKey = mockHashedItemStore.setItem.firstCall.args[0];
-      expect(appQuery[stateParamKey]).to.eql(hashKey);
-    });
-
-    it('if using multiple States', () => {
-      const stateParamKey1 = 'testParam1';
-      const stateParamKey2 = 'testParam2';
-      const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=(yes:!t)&${stateParamKey2}=(yes:!f)`;
-      const mockHashedItemStore = {
-        getItem: () => null,
-        setItem: sinon.stub().returns(true)
-      };
-      const state1 = new State(stateParamKey1, {}, mockHashedItemStore);
-      const state2 = new State(stateParamKey2, {}, mockHashedItemStore);
-
-      const actualUrl = hashUrl([state1, state2], url);
-
-      expect(mockHashedItemStore.setItem.calledTwice).to.be(true);
-
-      const appQuery = getAppQuery(actualUrl);
-
-      const hashKey1 = mockHashedItemStore.setItem.firstCall.args[0];
-      const hashKey2 = mockHashedItemStore.setItem.secondCall.args[0];
-      expect(appQuery[stateParamKey1]).to.eql(hashKey1);
-      expect(appQuery[stateParamKey2]).to.eql(hashKey2);
-    });
-  });
-});
diff --git a/src/legacy/ui/public/state_management/state_hashing/__tests__/unhash_url.js b/src/legacy/ui/public/state_management/state_hashing/__tests__/unhash_url.js
deleted file mode 100644
index 671194ecb50f555..000000000000000
--- a/src/legacy/ui/public/state_management/state_hashing/__tests__/unhash_url.js
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import expect from '@kbn/expect';
-import ngMock from 'ng_mock';
-import sinon from 'sinon';
-
-import { StateProvider } from '../../state';
-import { unhashUrl } from '..';
-
-describe('unhashUrl', () => {
-  let unhashableStates;
-
-  beforeEach(ngMock.module('kibana'));
-
-  beforeEach(ngMock.inject(Private => {
-    const State = Private(StateProvider);
-    const unhashableState = new State('testParam');
-    sinon.stub(unhashableState, 'translateHashToRison').withArgs('hash').returns('replacement');
-    unhashableStates = [unhashableState];
-  }));
-
-  describe('does nothing', () => {
-    it('if missing input', () => {
-      expect(() => {
-        unhashUrl();
-      }).to.not.throwError();
-    });
-
-    it('if just a host and port', () => {
-      const url = 'https://localhost:5601';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if just a path', () => {
-      const url = 'https://localhost:5601/app/kibana';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if just a path and query', () => {
-      const url = 'https://localhost:5601/app/kibana?foo=bar';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if empty hash with query', () => {
-      const url = 'https://localhost:5601/app/kibana?foo=bar#';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if empty hash without query', () => {
-      const url = 'https://localhost:5601/app/kibana#';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if hash is just a path', () => {
-      const url = 'https://localhost:5601/app/kibana#/discover';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-
-    it('if hash does not have matching query string vals', () => {
-      const url = 'https://localhost:5601/app/kibana#/discover?foo=bar';
-      expect(unhashUrl(url, unhashableStates)).to.be(url);
-    });
-  });
-
-  it('replaces query string vals in hash for matching states with output of state.toRISON()', () => {
-    const urlWithHashes = 'https://localhost:5601/#/?foo=bar&testParam=hash';
-    const exp = 'https://localhost:5601/#/?foo=bar&testParam=replacement';
-    expect(unhashUrl(urlWithHashes, unhashableStates)).to.be(exp);
-  });
-});
diff --git a/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.test.ts b/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.test.ts
new file mode 100644
index 000000000000000..8a298be8636c850
--- /dev/null
+++ b/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.test.ts
@@ -0,0 +1,286 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { mockSessionStorage } from '../state_storage/mock';
+import { HashedItemStore } from '../state_storage/hashed_item_store';
+import { hashUrl, unhashUrl } from './hash_unhash_url';
+
+describe('hash unhash url', () => {
+  beforeEach(() => {
+    mockSessionStorage.clear();
+    mockSessionStorage.setStubbedSizeLimit(5000000);
+  });
+
+  describe('hash url', () => {
+    describe('does nothing', () => {
+      it('if missing input', () => {
+        expect(() => {
+          // @ts-ignore
+          hashUrl();
+        }).not.toThrowError();
+      });
+
+      it('if url is empty', () => {
+        const url = '';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if just a host and port', () => {
+        const url = 'https://localhost:5601';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if just a path', () => {
+        const url = 'https://localhost:5601/app/kibana';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if just a path and query', () => {
+        const url = 'https://localhost:5601/app/kibana?foo=bar';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if empty hash with query', () => {
+        const url = 'https://localhost:5601/app/kibana?foo=bar#';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if query parameter matches and there is no hash', () => {
+        const url = 'https://localhost:5601/app/kibana?testParam=(yes:!t)';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it(`if query parameter matches and it's before the hash`, () => {
+        const url = 'https://localhost:5601/app/kibana?testParam=(yes:!t)';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if empty hash without query', () => {
+        const url = 'https://localhost:5601/app/kibana#';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if hash is just a path', () => {
+        const url = 'https://localhost:5601/app/kibana#/discover';
+        expect(hashUrl(url)).toBe(url);
+      });
+
+      it('if hash does not have matching query string vals', () => {
+        const url = 'https://localhost:5601/app/kibana#/discover?foo=bar';
+        expect(hashUrl(url)).toBe(url);
+      });
+    });
+
+    describe('replaces expanded state with hash', () => {
+      it('if uses single state param', () => {
+        const stateParamKey = '_g';
+        const stateParamValue = '(yes:!t)';
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey}=${stateParamValue}`;
+        const result = hashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=h@4e60e02"`
+        );
+        expect(mockSessionStorage.getItem('kbn.hashedItemsIndex.v1')).toBeTruthy();
+        expect(mockSessionStorage.getItem('h@4e60e02')).toEqual(JSON.stringify({ yes: true }));
+      });
+
+      it('if uses multiple states params', () => {
+        const stateParamKey1 = '_g';
+        const stateParamValue1 = '(yes:!t)';
+        const stateParamKey2 = '_a';
+        const stateParamValue2 = '(yes:!f)';
+        const stateParamKey3 = '_b';
+        const stateParamValue3 = '(yes:!f)';
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValue1}&${stateParamKey2}=${stateParamValue2}&${stateParamKey3}=${stateParamValue3}`;
+        const result = hashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=h@4e60e02&_a=h@61fa078&_b=(yes:!f)"`
+        );
+        expect(mockSessionStorage.getItem('h@4e60e02')).toEqual(JSON.stringify({ yes: true }));
+        expect(mockSessionStorage.getItem('h@61fa078')).toEqual(JSON.stringify({ yes: false }));
+        if (!HashedItemStore.PERSISTED_INDEX_KEY) {
+          // This is very brittle and depends upon HashedItemStore implementation details,
+          // so let's protect ourselves from accidentally breaking this test.
+          throw new Error('Missing HashedItemStore.PERSISTED_INDEX_KEY');
+        }
+        expect(mockSessionStorage.getItem(HashedItemStore.PERSISTED_INDEX_KEY)).toBeTruthy();
+        expect(mockSessionStorage.length).toBe(3);
+      });
+
+      it('hashes only whitelisted properties', () => {
+        const stateParamKey1 = '_g';
+        const stateParamValue1 = '(yes:!t)';
+        const stateParamKey2 = '_a';
+        const stateParamValue2 = '(yes:!f)';
+        const stateParamKey3 = '_someother';
+        const stateParamValue3 = '(yes:!f)';
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValue1}&${stateParamKey2}=${stateParamValue2}&${stateParamKey3}=${stateParamValue3}`;
+        const result = hashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=h@4e60e02&_a=h@61fa078&_someother=(yes:!f)"`
+        );
+
+        expect(mockSessionStorage.length).toBe(3); // 2 hashes + HashedItemStoreSingleton.PERSISTED_INDEX_KEY
+      });
+    });
+
+    it('throws error if unable to hash url', () => {
+      const stateParamKey1 = '_g';
+      const stateParamValue1 = '(yes:!t)';
+      mockSessionStorage.setStubbedSizeLimit(1);
+
+      const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValue1}`;
+      expect(() => hashUrl(url)).toThrowError();
+    });
+  });
+
+  describe('unhash url', () => {
+    describe('does nothing', () => {
+      it('if missing input', () => {
+        expect(() => {
+          // @ts-ignore
+        }).not.toThrowError();
+      });
+
+      it('if just a host and port', () => {
+        const url = 'https://localhost:5601';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if just a path', () => {
+        const url = 'https://localhost:5601/app/kibana';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if just a path and query', () => {
+        const url = 'https://localhost:5601/app/kibana?foo=bar';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if empty hash with query', () => {
+        const url = 'https://localhost:5601/app/kibana?foo=bar#';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if empty hash without query', () => {
+        const url = 'https://localhost:5601/app/kibana#';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if hash is just a path', () => {
+        const url = 'https://localhost:5601/app/kibana#/discover';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it('if hash does not have matching query string vals', () => {
+        const url = 'https://localhost:5601/app/kibana#/discover?foo=bar';
+        expect(unhashUrl(url)).toBe(url);
+      });
+
+      it("if hash has matching query, but it isn't hashed", () => {
+        const stateParamKey = '_g';
+        const stateParamValue = '(yes:!t)';
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey}=${stateParamValue}`;
+        expect(unhashUrl(url)).toBe(url);
+      });
+    });
+
+    describe('replaces expanded state with hash', () => {
+      it('if uses single state param', () => {
+        const stateParamKey = '_g';
+        const stateParamValueHashed = 'h@4e60e02';
+        const state = { yes: true };
+        mockSessionStorage.setItem(stateParamValueHashed, JSON.stringify(state));
+
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey}=${stateParamValueHashed}`;
+        const result = unhashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=(yes:!t)"`
+        );
+      });
+
+      it('if uses multiple state param', () => {
+        const stateParamKey1 = '_g';
+        const stateParamValueHashed1 = 'h@4e60e02';
+        const state1 = { yes: true };
+
+        const stateParamKey2 = '_a';
+        const stateParamValueHashed2 = 'h@61fa078';
+        const state2 = { yes: false };
+
+        mockSessionStorage.setItem(stateParamValueHashed1, JSON.stringify(state1));
+        mockSessionStorage.setItem(stateParamValueHashed2, JSON.stringify(state2));
+
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValueHashed1}&${stateParamKey2}=${stateParamValueHashed2}`;
+        const result = unhashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=(yes:!t)&_a=(yes:!f)"`
+        );
+      });
+
+      it('unhashes only whitelisted properties', () => {
+        const stateParamKey1 = '_g';
+        const stateParamValueHashed1 = 'h@4e60e02';
+        const state1 = { yes: true };
+
+        const stateParamKey2 = '_a';
+        const stateParamValueHashed2 = 'h@61fa078';
+        const state2 = { yes: false };
+
+        const stateParamKey3 = '_someother';
+        const stateParamValueHashed3 = 'h@61fa078';
+        const state3 = { yes: false };
+
+        mockSessionStorage.setItem(stateParamValueHashed1, JSON.stringify(state1));
+        mockSessionStorage.setItem(stateParamValueHashed2, JSON.stringify(state2));
+        mockSessionStorage.setItem(stateParamValueHashed3, JSON.stringify(state3));
+
+        const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValueHashed1}&${stateParamKey2}=${stateParamValueHashed2}&${stateParamKey3}=${stateParamValueHashed3}`;
+        const result = unhashUrl(url);
+        expect(result).toMatchInlineSnapshot(
+          `"https://localhost:5601/app/kibana#/discover?foo=bar&_g=(yes:!t)&_a=(yes:!f)&_someother=h@61fa078"`
+        );
+      });
+    });
+
+    it('throws error if unable to restore the url', () => {
+      const stateParamKey1 = '_g';
+      const stateParamValueHashed1 = 'h@4e60e02';
+
+      const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValueHashed1}`;
+      expect(() => unhashUrl(url)).toThrowErrorMatchingInlineSnapshot(
+        `"Unable to completely restore the URL, be sure to use the share functionality."`
+      );
+    });
+  });
+
+  describe('hash unhash url integration', () => {
+    it('hashing and unhashing url should produce the same result', () => {
+      const stateParamKey1 = '_g';
+      const stateParamValue1 = '(yes:!t)';
+      const stateParamKey2 = '_a';
+      const stateParamValue2 = '(yes:!f)';
+      const stateParamKey3 = '_someother';
+      const stateParamValue3 = '(yes:!f)';
+      const url = `https://localhost:5601/app/kibana#/discover?foo=bar&${stateParamKey1}=${stateParamValue1}&${stateParamKey2}=${stateParamValue2}&${stateParamKey3}=${stateParamValue3}`;
+      const result = unhashUrl(hashUrl(url));
+      expect(url).toEqual(result);
+    });
+  });
+});
diff --git a/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.ts b/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.ts
new file mode 100644
index 000000000000000..345924b92467dca
--- /dev/null
+++ b/src/legacy/ui/public/state_management/state_hashing/hash_unhash_url.ts
@@ -0,0 +1,157 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { i18n } from '@kbn/i18n';
+import rison, { RisonObject } from 'rison-node';
+import { stringify as stringifyQueryString } from 'querystring';
+import encodeUriQuery from 'encode-uri-query';
+import { format as formatUrl, parse as parseUrl } from 'url';
+import { HashedItemStoreSingleton } from '../state_storage';
+import { createStateHash, isStateHash } from './state_hash';
+
+export type IParsedUrlQuery = Record<string, any>;
+
+interface IUrlQueryMapperOptions {
+  hashableParams: string[];
+}
+export type IUrlQueryReplacerOptions = IUrlQueryMapperOptions;
+
+export const unhashQuery = createQueryMapper(stateHashToRisonState);
+export const hashQuery = createQueryMapper(risonStateToStateHash);
+
+export const unhashUrl = createQueryReplacer(unhashQuery);
+export const hashUrl = createQueryReplacer(hashQuery);
+
+// naive hack, but this allows to decouple these utils from AppState, GlobalState for now
+// when removing AppState, GlobalState and migrating to IState containers,
+// need to make sure that apps explicitly passing this whitelist to hash
+const __HACK_HARDCODED_LEGACY_HASHABLE_PARAMS = ['_g', '_a', '_s'];
+function createQueryMapper(queryParamMapper: (q: string) => string | null) {
+  return (
+    query: IParsedUrlQuery,
+    options: IUrlQueryMapperOptions = {
+      hashableParams: __HACK_HARDCODED_LEGACY_HASHABLE_PARAMS,
+    }
+  ) =>
+    Object.fromEntries(
+      Object.entries(query || {}).map(([name, value]) => {
+        if (!options.hashableParams.includes(name)) return [name, value];
+        return [name, queryParamMapper(value) || value];
+      })
+    );
+}
+
+function createQueryReplacer(
+  queryMapper: (q: IParsedUrlQuery, options?: IUrlQueryMapperOptions) => IParsedUrlQuery,
+  options?: IUrlQueryReplacerOptions
+) {
+  return (url: string) => {
+    if (!url) return url;
+
+    const parsedUrl = parseUrl(url, true);
+    if (!parsedUrl.hash) return url;
+
+    const appUrl = parsedUrl.hash.slice(1); // trim the #
+    if (!appUrl) return url;
+
+    const appUrlParsed = parseUrl(appUrl, true);
+    if (!appUrlParsed.query) return url;
+
+    const changedAppQuery = queryMapper(appUrlParsed.query, options);
+
+    // encodeUriQuery implements the less-aggressive encoding done naturally by
+    // the browser. We use it to generate the same urls the browser would
+    const changedAppQueryString = stringifyQueryString(changedAppQuery, undefined, undefined, {
+      encodeURIComponent: encodeUriQuery,
+    });
+
+    return formatUrl({
+      ...parsedUrl,
+      hash: formatUrl({
+        pathname: appUrlParsed.pathname,
+        search: changedAppQueryString,
+      }),
+    });
+  };
+}
+
+// TODO: this helper should be merged with or replaced by
+// src/legacy/ui/public/state_management/state_storage/hashed_item_store.ts
+// maybe to become simplified stateless version
+export function retrieveState(stateHash: string): RisonObject {
+  const json = HashedItemStoreSingleton.getItem(stateHash);
+  const throwUnableToRestoreUrlError = () => {
+    throw new Error(
+      i18n.translate('common.ui.stateManagement.unableToRestoreUrlErrorMessage', {
+        defaultMessage:
+          'Unable to completely restore the URL, be sure to use the share functionality.',
+      })
+    );
+  };
+  if (json === null) {
+    return throwUnableToRestoreUrlError();
+  }
+  try {
+    return JSON.parse(json);
+  } catch (e) {
+    return throwUnableToRestoreUrlError();
+  }
+}
+
+// TODO: this helper should be merged with or replaced by
+// src/legacy/ui/public/state_management/state_storage/hashed_item_store.ts
+// maybe to become simplified stateless version
+export function persistState(state: RisonObject): string {
+  const json = JSON.stringify(state);
+  const hash = createStateHash(json);
+
+  const isItemSet = HashedItemStoreSingleton.setItem(hash, json);
+  if (isItemSet) return hash;
+  // If we ran out of space trying to persist the state, notify the user.
+  const message = i18n.translate(
+    'common.ui.stateManagement.unableToStoreHistoryInSessionErrorMessage',
+    {
+      defaultMessage:
+        'Kibana is unable to store history items in your session ' +
+        `because it is full and there don't seem to be items any items safe ` +
+        'to delete.\n\n' +
+        'This can usually be fixed by moving to a fresh tab, but could ' +
+        'be caused by a larger issue. If you are seeing this message regularly, ' +
+        'please file an issue at {gitHubIssuesUrl}.',
+      values: { gitHubIssuesUrl: 'https://github.com/elastic/kibana/issues' },
+    }
+  );
+  throw new Error(message);
+}
+
+function stateHashToRisonState(stateHashOrRison: string): string {
+  if (isStateHash(stateHashOrRison)) {
+    return rison.encode(retrieveState(stateHashOrRison));
+  }
+
+  return stateHashOrRison;
+}
+
+function risonStateToStateHash(stateHashOrRison: string): string | null {
+  if (isStateHash(stateHashOrRison)) {
+    return stateHashOrRison;
+  }
+
+  return persistState(rison.decode(stateHashOrRison) as RisonObject);
+}
diff --git a/src/legacy/ui/public/state_management/state_hashing/hash_url.js b/src/legacy/ui/public/state_management/state_hashing/hash_url.js
deleted file mode 100644
index 973266fcf868525..000000000000000
--- a/src/legacy/ui/public/state_management/state_hashing/hash_url.js
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import encodeUriQuery from 'encode-uri-query';
-import rison from 'rison-node';
-import { parse as parseUrl, format as formatUrl } from 'url';
-import { stringify as stringifyQuerystring } from 'querystring';
-
-const conservativeStringifyQuerystring = (query) => {
-  return stringifyQuerystring(query, null, null, {
-    encodeURIComponent: encodeUriQuery
-  });
-};
-
-const hashStateInQuery = (state, query) => {
-  const name = state.getQueryParamName();
-  const value = query[name];
-  if (!value) {
-    return { name, value };
-  }
-
-  const decodedValue = rison.decode(value);
-  const hashedValue = state.toQueryParam(decodedValue);
-  return { name, value: hashedValue };
-};
-
-const hashStatesInQuery = (states, query) => {
-  const hashedQuery = states.reduce((result, state) => {
-    const { name, value } = hashStateInQuery(state, query);
-    if (value) {
-      result[name] = value;
-    }
-    return result;
-  }, {});
-
-
-  return {
-    ...query,
-    ...hashedQuery
-  };
-};
-
-export const hashUrl = (states, redirectUrl) => {
-  // we need states to proceed, throwing an error if we don't have any
-  if (states === null || !states.length) {
-    throw new Error('states parameter must be an Array with length greater than 0');
-  }
-
-  const parsedUrl = parseUrl(redirectUrl);
-  // if we don't have a hash, we return the redirectUrl without hashing anything
-  if (!parsedUrl.hash) {
-    return redirectUrl;
-  }
-
-  // The URLs that we use aren't "conventional" and the hash is sometimes appearing before
-  // the querystring, even though conventionally they appear after it. The parsedUrl
-  // is the entire URL, and the parsedAppUrl is everything after the hash.
-  //
-  // EXAMPLE
-  // parsedUrl: /app/kibana#/visualize/edit/somelongguid?g=()&a=()
-  // parsedAppUrl: /visualize/edit/somelongguid?g=()&a=()
-  const parsedAppUrl = parseUrl(parsedUrl.hash.slice(1), true);
-
-  // the parsedAppUrl actually has the query that we care about
-  const query = parsedAppUrl.query;
-
-  const newQuery = hashStatesInQuery(states, query);
-
-  const newHash = formatUrl({
-    search: conservativeStringifyQuerystring(newQuery),
-    pathname: parsedAppUrl.pathname
-  });
-
-  return formatUrl({
-    hash: `#${newHash}`,
-    host: parsedUrl.host,
-    search: parsedUrl.search,
-    pathname: parsedUrl.pathname,
-    protocol: parsedUrl.protocol,
-  });
-};
diff --git a/src/legacy/ui/public/state_management/state_hashing/index.d.ts b/src/legacy/ui/public/state_management/state_hashing/index.ts
similarity index 85%
rename from src/legacy/ui/public/state_management/state_hashing/index.d.ts
rename to src/legacy/ui/public/state_management/state_hashing/index.ts
index 163d9ed07f2cc30..6225202f909781a 100644
--- a/src/legacy/ui/public/state_management/state_hashing/index.d.ts
+++ b/src/legacy/ui/public/state_management/state_hashing/index.ts
@@ -17,4 +17,5 @@
  * under the License.
  */
 
-export function unhashUrl(url: string, kbnStates: any[]): any;
+export { hashUrl, unhashUrl, hashQuery, unhashQuery } from './hash_unhash_url';
+export { createStateHash, isStateHash } from './state_hash';
diff --git a/src/legacy/ui/public/state_management/state_storage/__tests__/state_hash.js b/src/legacy/ui/public/state_management/state_hashing/state_hash.test.ts
similarity index 62%
rename from src/legacy/ui/public/state_management/state_storage/__tests__/state_hash.js
rename to src/legacy/ui/public/state_management/state_hashing/state_hash.test.ts
index 71fcf33274fc653..5cbf0c8fdcfc54b 100644
--- a/src/legacy/ui/public/state_management/state_storage/__tests__/state_hash.js
+++ b/src/legacy/ui/public/state_management/state_hashing/state_hash.test.ts
@@ -17,58 +17,55 @@
  * under the License.
  */
 
-import expect from '@kbn/expect';
 import { encode as encodeRison } from 'rison-node';
-
-import {
-  createStateHash,
-  isStateHash,
-} from '../state_hash';
+import { mockSessionStorage } from '../state_storage/mock';
+import { createStateHash, isStateHash } from '../state_hashing';
 
 describe('stateHash', () => {
-  const existingJsonProvider = () => null;
+  beforeEach(() => {
+    mockSessionStorage.clear();
+  });
 
   describe('#createStateHash', () => {
-
-    describe('returns a hash', () => {
+    it('returns a hash', () => {
       const json = JSON.stringify({ a: 'a' });
-      const hash = createStateHash(json, existingJsonProvider);
-      expect(isStateHash(hash)).to.be(true);
+      const hash = createStateHash(json);
+      expect(isStateHash(hash)).toBe(true);
     });
 
-    describe('returns the same hash for the same input', () => {
+    it('returns the same hash for the same input', () => {
       const json = JSON.stringify({ a: 'a' });
-      const hash1 = createStateHash(json, existingJsonProvider);
-      const hash2 = createStateHash(json, existingJsonProvider);
-      expect(hash1).to.equal(hash2);
+      const hash1 = createStateHash(json);
+      const hash2 = createStateHash(json);
+      expect(hash1).toEqual(hash2);
     });
 
-    describe('returns a different hash for different input', () => {
+    it('returns a different hash for different input', () => {
       const json1 = JSON.stringify({ a: 'a' });
-      const hash1 = createStateHash(json1, existingJsonProvider);
+      const hash1 = createStateHash(json1);
 
       const json2 = JSON.stringify({ a: 'b' });
-      const hash2 = createStateHash(json2, existingJsonProvider);
-      expect(hash1).to.not.equal(hash2);
+      const hash2 = createStateHash(json2);
+      expect(hash1).not.toEqual(hash2);
     });
   });
 
   describe('#isStateHash', () => {
     it('returns true for values created using #createStateHash', () => {
       const json = JSON.stringify({ a: 'a' });
-      const hash = createStateHash(json, existingJsonProvider);
-      expect(isStateHash(hash)).to.be(true);
+      const hash = createStateHash(json);
+      expect(isStateHash(hash)).toBe(true);
     });
 
     it('returns false for values not created using #createStateHash', () => {
       const json = JSON.stringify({ a: 'a' });
-      expect(isStateHash(json)).to.be(false);
+      expect(isStateHash(json)).toBe(false);
     });
 
     it('returns false for RISON', () => {
       // We're storing RISON in the URL, so let's test against this specifically.
       const rison = encodeRison({ a: 'a' });
-      expect(isStateHash(rison)).to.be(false);
+      expect(isStateHash(rison)).toBe(false);
     });
   });
 });
diff --git a/src/legacy/ui/public/state_management/state_storage/state_hash.js b/src/legacy/ui/public/state_management/state_hashing/state_hash.ts
similarity index 76%
rename from src/legacy/ui/public/state_management/state_storage/state_hash.js
rename to src/legacy/ui/public/state_management/state_hashing/state_hash.ts
index 0e8dc2c05c0f281..a7a75eec63ccb20 100644
--- a/src/legacy/ui/public/state_management/state_storage/state_hash.js
+++ b/src/legacy/ui/public/state_management/state_hashing/state_hash.ts
@@ -17,12 +17,16 @@
  * under the License.
  */
 
-import { Sha256 } from '../../../../../core/public/utils/';
+import { Sha256 } from '../../../../../core/public/utils';
+import { HashedItemStoreSingleton } from '../state_storage';
 
 // This prefix is used to identify hash strings that have been encoded in the URL.
 const HASH_PREFIX = 'h@';
 
-export function createStateHash(json, existingJsonProvider) {
+export function createStateHash(
+  json: string,
+  existingJsonProvider?: (hash: string) => string | null // TODO: temp while state.js relies on this in tests
+) {
   if (typeof json !== 'string') {
     throw new Error('createHash only accepts strings (JSON).');
   }
@@ -36,13 +40,15 @@ export function createStateHash(json, existingJsonProvider) {
   // b) or has been used already, but with the JSON we're currently hashing.
   for (let i = 7; i < hash.length; i++) {
     shortenedHash = hash.slice(0, i);
-    const existingJson = existingJsonProvider(shortenedHash);
+    const existingJson = existingJsonProvider
+      ? existingJsonProvider(shortenedHash)
+      : HashedItemStoreSingleton.getItem(shortenedHash);
     if (existingJson === null || existingJson === json) break;
   }
 
   return `${HASH_PREFIX}${shortenedHash}`;
 }
 
-export function isStateHash(str) {
+export function isStateHash(str: string) {
   return String(str).indexOf(HASH_PREFIX) === 0;
 }
diff --git a/src/legacy/ui/public/state_management/state_hashing/unhash_query_string.ts b/src/legacy/ui/public/state_management/state_hashing/unhash_query_string.ts
deleted file mode 100644
index 242b840282f39e7..000000000000000
--- a/src/legacy/ui/public/state_management/state_hashing/unhash_query_string.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import { mapValues } from 'lodash';
-import { ParsedUrlQuery } from 'querystring';
-import { State } from '../state';
-
-/**
- * Takes in a parsed url query and state objects, finding the state objects that match the query parameters and expanding
- * the hashed state. For example, a url query string like '?_a=@12353&_g=@19028df' will become
- * '?_a=[expanded app state here]&_g=[expanded global state here]. This is used when storeStateInSessionStorage is turned on.
- */
-export function unhashQueryString(
-  parsedQueryString: ParsedUrlQuery,
-  states: State[]
-): ParsedUrlQuery {
-  return mapValues(parsedQueryString, (val, key) => {
-    const state = states.find(s => key === s.getQueryParamName());
-    return state ? state.translateHashToRison(val) : val;
-  });
-}
diff --git a/src/legacy/ui/public/state_management/state_hashing/unhash_url.js b/src/legacy/ui/public/state_management/state_hashing/unhash_url.js
deleted file mode 100644
index 272237a8b81effd..000000000000000
--- a/src/legacy/ui/public/state_management/state_hashing/unhash_url.js
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import {
-  parse as parseUrl,
-  format as formatUrl,
-} from 'url';
-
-import encodeUriQuery from 'encode-uri-query';
-
-import {
-  stringify as stringifyQueryString
-} from 'querystring';
-
-import { unhashQueryString } from './unhash_query_string';
-
-export function unhashUrl(urlWithHashes, states) {
-  if (!urlWithHashes) return urlWithHashes;
-
-  const urlWithHashesParsed = parseUrl(urlWithHashes, true);
-  if (!urlWithHashesParsed.hostname) {
-    // passing a url like "localhost:5601" or "/app/kibana" should be prevented
-    throw new TypeError(
-      'Only absolute urls should be passed to `unhashUrl()`. ' +
-      'Unable to detect url hostname.'
-    );
-  }
-
-  if (!urlWithHashesParsed.hash) return urlWithHashes;
-
-  const appUrl = urlWithHashesParsed.hash.slice(1); // trim the #
-  if (!appUrl) return urlWithHashes;
-
-  const appUrlParsed = parseUrl(urlWithHashesParsed.hash.slice(1), true);
-  if (!appUrlParsed.query) return urlWithHashes;
-
-  const appQueryWithoutHashes = unhashQueryString(appUrlParsed.query || {}, states);
-
-  // encodeUriQuery implements the less-aggressive encoding done naturally by
-  // the browser. We use it to generate the same urls the browser would
-  const appQueryStringWithoutHashes = stringifyQueryString(appQueryWithoutHashes, null, null, {
-    encodeURIComponent: encodeUriQuery
-  });
-
-  return formatUrl({
-    ...urlWithHashesParsed,
-    hash: formatUrl({
-      pathname: appUrlParsed.pathname,
-      search: appQueryStringWithoutHashes,
-    })
-  });
-}
diff --git a/src/legacy/ui/public/state_management/state_storage/__tests__/hashed_item_store.js b/src/legacy/ui/public/state_management/state_storage/hashed_item_store.test.ts
similarity index 68%
rename from src/legacy/ui/public/state_management/state_storage/__tests__/hashed_item_store.js
rename to src/legacy/ui/public/state_management/state_storage/hashed_item_store.test.ts
index dfb726ce53299d1..3eb4e045f2cf151 100644
--- a/src/legacy/ui/public/state_management/state_storage/__tests__/hashed_item_store.js
+++ b/src/legacy/ui/public/state_management/state_storage/hashed_item_store.test.ts
@@ -17,22 +17,19 @@
  * under the License.
  */
 
-import expect from '@kbn/expect';
-import sinon from 'sinon';
-
 import { StubBrowserStorage } from 'test_utils/stub_browser_storage';
-import { HashedItemStore } from '../hashed_item_store';
+import { HashedItemStore } from './hashed_item_store';
 
 describe('hashedItemStore', () => {
   describe('interface', () => {
     describe('#constructor', () => {
       it('retrieves persisted index from sessionStorage', () => {
         const sessionStorage = new StubBrowserStorage();
-        sinon.spy(sessionStorage, 'getItem');
+        const spy = jest.spyOn(sessionStorage, 'getItem');
 
         new HashedItemStore(sessionStorage);
-        sinon.assert.calledWith(sessionStorage.getItem, HashedItemStore.PERSISTED_INDEX_KEY);
-        sessionStorage.getItem.restore();
+        expect(spy).toBeCalledWith(HashedItemStore.PERSISTED_INDEX_KEY);
+        spy.mockReset();
       });
 
       it('sorts indexed items by touched property', () => {
@@ -57,14 +54,14 @@ describe('hashedItemStore', () => {
         sessionStorage.setItem(HashedItemStore.PERSISTED_INDEX_KEY, JSON.stringify({ a, b, c }));
 
         const hashedItemStore = new HashedItemStore(sessionStorage);
-        expect(hashedItemStore._indexedItems).to.eql([a, c, b]);
+        expect((hashedItemStore as any).indexedItems).toEqual([a, c, b]);
       });
     });
 
     describe('#setItem', () => {
       describe('if the item exists in sessionStorage', () => {
-        let sessionStorage;
-        let hashedItemStore;
+        let sessionStorage: Storage;
+        let hashedItemStore: HashedItemStore;
         const hash = 'a';
         const item = JSON.stringify({});
 
@@ -75,19 +72,19 @@ describe('hashedItemStore', () => {
 
         it('persists the item in sessionStorage', () => {
           hashedItemStore.setItem(hash, item);
-          expect(sessionStorage.getItem(hash)).to.equal(item);
+          expect(sessionStorage.getItem(hash)).toEqual(item);
         });
 
         it('returns true', () => {
           const result = hashedItemStore.setItem(hash, item);
-          expect(result).to.equal(true);
+          expect(result).toEqual(true);
         });
       });
 
       describe(`if the item doesn't exist in sessionStorage`, () => {
         describe(`if there's storage space`, () => {
-          let sessionStorage;
-          let hashedItemStore;
+          let sessionStorage: Storage;
+          let hashedItemStore: HashedItemStore;
           const hash = 'a';
           const item = JSON.stringify({});
 
@@ -98,32 +95,31 @@ describe('hashedItemStore', () => {
 
           it('persists the item in sessionStorage', () => {
             hashedItemStore.setItem(hash, item);
-            expect(sessionStorage.getItem(hash)).to.equal(item);
+            expect(sessionStorage.getItem(hash)).toEqual(item);
           });
 
           it('returns true', () => {
             const result = hashedItemStore.setItem(hash, item);
-            expect(result).to.equal(true);
+            expect(result).toEqual(true);
           });
         });
 
         describe(`if there isn't storage space`, () => {
-          let fakeTimer;
-          let sessionStorage;
-          let hashedItemStore;
-          let storageSizeLimit;
+          let sessionStorage: Storage;
+          let hashedItemStore: HashedItemStore;
+          let storageSizeLimit: number;
           const hash = 'a';
           const item = JSON.stringify({});
 
-          function setItemLater(hash, item) {
+          function setItemLater(_hash: string, _item: string) {
             // Move time forward, so this item will be "touched" most recently.
-            fakeTimer.tick(1);
-            return hashedItemStore.setItem(hash, item);
+            jest.advanceTimersByTime(1);
+            return hashedItemStore.setItem(_hash, _item);
           }
 
           beforeEach(() => {
             // Control time.
-            fakeTimer = sinon.useFakeTimers(Date.now());
+            jest.useFakeTimers();
 
             sessionStorage = new StubBrowserStorage();
             hashedItemStore = new HashedItemStore(sessionStorage);
@@ -141,29 +137,29 @@ describe('hashedItemStore', () => {
 
           afterEach(() => {
             // Stop controlling time.
-            fakeTimer.restore();
+            jest.useRealTimers();
           });
 
           describe('and the item will fit', () => {
             it('removes older items until the new item fits', () => {
               setItemLater(hash, item);
-              expect(sessionStorage.getItem('b')).to.equal(null);
-              expect(sessionStorage.getItem('c')).to.equal(item);
+              expect(sessionStorage.getItem('b')).toEqual(null);
+              expect(sessionStorage.getItem('c')).toEqual(item);
             });
 
             it('persists the item in sessionStorage', () => {
               setItemLater(hash, item);
-              expect(sessionStorage.getItem(hash)).to.equal(item);
+              expect(sessionStorage.getItem(hash)).toEqual(item);
             });
 
             it('returns true', () => {
               const result = setItemLater(hash, item);
-              expect(result).to.equal(true);
+              expect(result).toEqual(true);
             });
           });
 
           describe(`and the item won't fit`, () => {
-            let itemTooBigToFit;
+            let itemTooBigToFit: string;
 
             beforeEach(() => {
               // Make sure the item is longer than the storage size limit.
@@ -176,18 +172,18 @@ describe('hashedItemStore', () => {
 
             it('removes all items', () => {
               setItemLater(hash, itemTooBigToFit);
-              expect(sessionStorage.getItem('b')).to.equal(null);
-              expect(sessionStorage.getItem('c')).to.equal(null);
+              expect(sessionStorage.getItem('b')).toEqual(null);
+              expect(sessionStorage.getItem('c')).toEqual(null);
             });
 
             it(`doesn't persist the item in sessionStorage`, () => {
               setItemLater(hash, itemTooBigToFit);
-              expect(sessionStorage.getItem(hash)).to.equal(null);
+              expect(sessionStorage.getItem(hash)).toEqual(null);
             });
 
             it('returns false', () => {
               const result = setItemLater(hash, itemTooBigToFit);
-              expect(result).to.equal(false);
+              expect(result).toEqual(false);
             });
           });
         });
@@ -196,25 +192,24 @@ describe('hashedItemStore', () => {
 
     describe('#getItem', () => {
       describe('if the item exists in sessionStorage', () => {
-        let fakeTimer;
-        let sessionStorage;
-        let hashedItemStore;
+        let sessionStorage: Storage;
+        let hashedItemStore: HashedItemStore;
 
-        function setItemLater(hash, item) {
+        function setItemLater(hash: string, item: string) {
           // Move time forward, so this item will be "touched" most recently.
-          fakeTimer.tick(1);
+          jest.advanceTimersByTime(1);
           return hashedItemStore.setItem(hash, item);
         }
 
-        function getItemLater(hash) {
+        function getItemLater(hash: string) {
           // Move time forward, so this item will be "touched" most recently.
-          fakeTimer.tick(1);
+          jest.advanceTimersByTime(1);
           return hashedItemStore.getItem(hash);
         }
 
         beforeEach(() => {
           // Control time.
-          fakeTimer = sinon.useFakeTimers(Date.now());
+          jest.useFakeTimers();
 
           sessionStorage = new StubBrowserStorage();
           hashedItemStore = new HashedItemStore(sessionStorage);
@@ -223,12 +218,12 @@ describe('hashedItemStore', () => {
 
         afterEach(() => {
           // Stop controlling time.
-          fakeTimer.restore();
+          jest.useRealTimers();
         });
 
         it('returns the item', () => {
           const retrievedItem = hashedItemStore.getItem('1');
-          expect(retrievedItem).to.be('a');
+          expect(retrievedItem).toBe('a');
         });
 
         it('prevents the item from being first to be removed when freeing up storage space', () => {
@@ -244,14 +239,14 @@ describe('hashedItemStore', () => {
 
           // Add a new item, causing the second item to be removed, but not the first.
           setItemLater('3', 'c');
-          expect(hashedItemStore.getItem('2')).to.equal(null);
-          expect(hashedItemStore.getItem('1')).to.equal('a');
+          expect(hashedItemStore.getItem('2')).toEqual(null);
+          expect(hashedItemStore.getItem('1')).toEqual('a');
         });
       });
 
       describe(`if the item doesn't exist in sessionStorage`, () => {
-        let sessionStorage;
-        let hashedItemStore;
+        let sessionStorage: Storage;
+        let hashedItemStore: HashedItemStore;
         const hash = 'a';
 
         beforeEach(() => {
@@ -261,40 +256,38 @@ describe('hashedItemStore', () => {
 
         it('returns null', () => {
           const retrievedItem = hashedItemStore.getItem(hash);
-          expect(retrievedItem).to.be(null);
+          expect(retrievedItem).toBe(null);
         });
       });
     });
   });
 
   describe('behavior', () => {
-    let fakeTimer;
-    let sessionStorage;
-    let hashedItemStore;
+    let sessionStorage: Storage;
+    let hashedItemStore: HashedItemStore;
 
-    function setItemLater(hash, item) {
+    function setItemLater(hash: string, item: string) {
       // Move time forward, so this item will be "touched" most recently.
-      fakeTimer.tick(1);
+      jest.advanceTimersByTime(1);
       return hashedItemStore.setItem(hash, item);
     }
 
-    function getItemLater(hash) {
+    function getItemLater(hash: string) {
       // Move time forward, so this item will be "touched" most recently.
-      fakeTimer.tick(1);
+      jest.advanceTimersByTime(1);
       return hashedItemStore.getItem(hash);
     }
 
     beforeEach(() => {
       // Control time.
-      fakeTimer = sinon.useFakeTimers(Date.now());
-
+      jest.useFakeTimers();
       sessionStorage = new StubBrowserStorage();
       hashedItemStore = new HashedItemStore(sessionStorage);
     });
 
     afterEach(() => {
       // Stop controlling time.
-      fakeTimer.restore();
+      jest.useRealTimers();
     });
 
     it('orders items to be removed based on when they were last retrieved', () => {
@@ -314,39 +307,39 @@ describe('hashedItemStore', () => {
       getItemLater('4');
 
       setItemLater('5', 'e');
-      expect(hashedItemStore.getItem('1')).to.equal(null);
-      expect(hashedItemStore.getItem('3')).to.equal('c');
-      expect(hashedItemStore.getItem('2')).to.equal('b');
-      expect(hashedItemStore.getItem('4')).to.equal('d');
-      expect(hashedItemStore.getItem('5')).to.equal('e');
+      expect(hashedItemStore.getItem('1')).toEqual(null);
+      expect(hashedItemStore.getItem('3')).toEqual('c');
+      expect(hashedItemStore.getItem('2')).toEqual('b');
+      expect(hashedItemStore.getItem('4')).toEqual('d');
+      expect(hashedItemStore.getItem('5')).toEqual('e');
 
       setItemLater('6', 'f');
-      expect(hashedItemStore.getItem('3')).to.equal(null);
-      expect(hashedItemStore.getItem('2')).to.equal('b');
-      expect(hashedItemStore.getItem('4')).to.equal('d');
-      expect(hashedItemStore.getItem('5')).to.equal('e');
-      expect(hashedItemStore.getItem('6')).to.equal('f');
+      expect(hashedItemStore.getItem('3')).toEqual(null);
+      expect(hashedItemStore.getItem('2')).toEqual('b');
+      expect(hashedItemStore.getItem('4')).toEqual('d');
+      expect(hashedItemStore.getItem('5')).toEqual('e');
+      expect(hashedItemStore.getItem('6')).toEqual('f');
 
       setItemLater('7', 'g');
-      expect(hashedItemStore.getItem('2')).to.equal(null);
-      expect(hashedItemStore.getItem('4')).to.equal('d');
-      expect(hashedItemStore.getItem('5')).to.equal('e');
-      expect(hashedItemStore.getItem('6')).to.equal('f');
-      expect(hashedItemStore.getItem('7')).to.equal('g');
+      expect(hashedItemStore.getItem('2')).toEqual(null);
+      expect(hashedItemStore.getItem('4')).toEqual('d');
+      expect(hashedItemStore.getItem('5')).toEqual('e');
+      expect(hashedItemStore.getItem('6')).toEqual('f');
+      expect(hashedItemStore.getItem('7')).toEqual('g');
 
       setItemLater('8', 'h');
-      expect(hashedItemStore.getItem('4')).to.equal(null);
-      expect(hashedItemStore.getItem('5')).to.equal('e');
-      expect(hashedItemStore.getItem('6')).to.equal('f');
-      expect(hashedItemStore.getItem('7')).to.equal('g');
-      expect(hashedItemStore.getItem('8')).to.equal('h');
+      expect(hashedItemStore.getItem('4')).toEqual(null);
+      expect(hashedItemStore.getItem('5')).toEqual('e');
+      expect(hashedItemStore.getItem('6')).toEqual('f');
+      expect(hashedItemStore.getItem('7')).toEqual('g');
+      expect(hashedItemStore.getItem('8')).toEqual('h');
 
       setItemLater('9', 'i');
-      expect(hashedItemStore.getItem('5')).to.equal(null);
-      expect(hashedItemStore.getItem('6')).to.equal('f');
-      expect(hashedItemStore.getItem('7')).to.equal('g');
-      expect(hashedItemStore.getItem('8')).to.equal('h');
-      expect(hashedItemStore.getItem('9')).to.equal('i');
+      expect(hashedItemStore.getItem('5')).toEqual(null);
+      expect(hashedItemStore.getItem('6')).toEqual('f');
+      expect(hashedItemStore.getItem('7')).toEqual('g');
+      expect(hashedItemStore.getItem('8')).toEqual('h');
+      expect(hashedItemStore.getItem('9')).toEqual('i');
     });
   });
 });
diff --git a/src/legacy/ui/public/state_management/state_storage/hashed_item_store.js b/src/legacy/ui/public/state_management/state_storage/hashed_item_store.ts
similarity index 74%
rename from src/legacy/ui/public/state_management/state_storage/hashed_item_store.js
rename to src/legacy/ui/public/state_management/state_storage/hashed_item_store.ts
index 71306524160722b..f49d993e1576006 100644
--- a/src/legacy/ui/public/state_management/state_storage/hashed_item_store.js
+++ b/src/legacy/ui/public/state_management/state_storage/hashed_item_store.ts
@@ -72,59 +72,66 @@
 
 import { pull, sortBy } from 'lodash';
 
+interface IndexedItem {
+  hash: string;
+  touched?: number; // Date.now()
+}
+
 export class HashedItemStore {
+  static readonly PERSISTED_INDEX_KEY = 'kbn.hashedItemsIndex.v1';
+  private sessionStorage: Storage;
+
+  // Store indexed items in descending order by touched (oldest first, newest last). We'll use
+  // this to remove older items when we run out of storage space.
+  private indexedItems: IndexedItem[] = [];
 
   /**
    * HashedItemStore uses objects called indexed items to refer to items that have been persisted
    * in sessionStorage. An indexed item is shaped {hash, touched}. The touched date is when the item
    * was last referenced by the browser history.
    */
-  constructor(sessionStorage) {
-    this._sessionStorage = sessionStorage;
-
-    // Store indexed items in descending order by touched (oldest first, newest last). We'll use
-    // this to remove older items when we run out of storage space.
-    this._indexedItems = [];
+  constructor(sessionStorage: Storage) {
+    this.sessionStorage = sessionStorage;
 
     // Potentially restore a previously persisted index. This happens when
     // we re-open a closed tab.
-    const persistedItemIndex = this._sessionStorage.getItem(HashedItemStore.PERSISTED_INDEX_KEY);
+    const persistedItemIndex = this.sessionStorage.getItem(HashedItemStore.PERSISTED_INDEX_KEY);
     if (persistedItemIndex) {
-      this._indexedItems = sortBy(JSON.parse(persistedItemIndex) || [], 'touched');
+      this.indexedItems = sortBy(JSON.parse(persistedItemIndex) || [], 'touched');
     }
   }
 
-  setItem(hash, item) {
-    const isItemPersisted = this._persistItem(hash, item);
+  setItem(hash: string, item: string): boolean {
+    const isItemPersisted = this.persistItem(hash, item);
 
     if (isItemPersisted) {
-      this._touchHash(hash);
+      this.touchHash(hash);
     }
 
     return isItemPersisted;
   }
 
-  getItem(hash) {
-    const item = this._sessionStorage.getItem(hash);
+  getItem(hash: string): string | null {
+    const item = this.sessionStorage.getItem(hash);
 
     if (item !== null) {
-      this._touchHash(hash);
+      this.touchHash(hash);
     }
 
     return item;
   }
 
-  _getIndexedItem(hash) {
-    return this._indexedItems.find(indexedItem => indexedItem.hash === hash);
+  private getIndexedItem(hash: string) {
+    return this.indexedItems.find(indexedItem => indexedItem.hash === hash);
   }
 
-  _persistItem(hash, item) {
+  private persistItem(hash: string, item: string): boolean {
     try {
-      this._sessionStorage.setItem(hash, item);
+      this.sessionStorage.setItem(hash, item);
       return true;
     } catch (e) {
       // If there was an error then we need to make some space for the item.
-      if (this._indexedItems.length === 0) {
+      if (this.indexedItems.length === 0) {
         // If there's nothing left to remove, then we've run out of space and we're trying to
         // persist too large an item.
         return false;
@@ -132,39 +139,39 @@ export class HashedItemStore {
 
       // We need to try to make some space for the item by removing older items (i.e. items that
       // haven't been accessed recently).
-      this._removeOldestItem();
+      this.removeOldestItem();
 
       // Try to persist again.
-      return this._persistItem(hash, item);
+      return this.persistItem(hash, item);
     }
   }
 
-  _removeOldestItem() {
-    const oldestIndexedItem = this._indexedItems.shift();
-    // Remove oldest item from storage.
-    this._sessionStorage.removeItem(oldestIndexedItem.hash);
+  private removeOldestItem() {
+    const oldestIndexedItem = this.indexedItems.shift();
+    if (oldestIndexedItem) {
+      // Remove oldest item from storage.
+      this.sessionStorage.removeItem(oldestIndexedItem.hash);
+    }
   }
 
-  _touchHash(hash) {
+  private touchHash(hash: string) {
     // Touching a hash indicates that it's been used recently, so it won't be the first in line
     // when we remove items to free up storage space.
 
     // either get or create an indexedItem
-    const indexedItem = this._getIndexedItem(hash) || { hash };
+    const indexedItem = this.getIndexedItem(hash) || { hash };
 
     // set/update the touched time to now so that it's the "newest" item in the index
-    indexedItem.touched =  Date.now();
+    indexedItem.touched = Date.now();
 
     // ensure that the item is last in the index
-    pull(this._indexedItems, indexedItem);
-    this._indexedItems.push(indexedItem);
+    pull(this.indexedItems, indexedItem);
+    this.indexedItems.push(indexedItem);
 
     // Regardless of whether this is a new or updated item, we need to persist the index.
-    this._sessionStorage.setItem(
+    this.sessionStorage.setItem(
       HashedItemStore.PERSISTED_INDEX_KEY,
-      JSON.stringify(this._indexedItems)
+      JSON.stringify(this.indexedItems)
     );
   }
 }
-
-HashedItemStore.PERSISTED_INDEX_KEY = 'kbn.hashedItemsIndex.v1';
diff --git a/src/legacy/ui/public/state_management/state_storage/hashed_item_store_singleton.js b/src/legacy/ui/public/state_management/state_storage/hashed_item_store_singleton.ts
similarity index 100%
rename from src/legacy/ui/public/state_management/state_storage/hashed_item_store_singleton.js
rename to src/legacy/ui/public/state_management/state_storage/hashed_item_store_singleton.ts
diff --git a/src/legacy/ui/public/state_management/state_storage/index.js b/src/legacy/ui/public/state_management/state_storage/index.ts
similarity index 92%
rename from src/legacy/ui/public/state_management/state_storage/index.js
rename to src/legacy/ui/public/state_management/state_storage/index.ts
index eb878fc88b5787e..8316e10fb8062f2 100644
--- a/src/legacy/ui/public/state_management/state_storage/index.js
+++ b/src/legacy/ui/public/state_management/state_storage/index.ts
@@ -18,8 +18,3 @@
  */
 
 export { HashedItemStoreSingleton } from './hashed_item_store_singleton';
-
-export {
-  createStateHash,
-  isStateHash,
-} from './state_hash';
diff --git a/src/legacy/ui/public/state_management/state_hashing/get_unhashable_states_provider.ts b/src/legacy/ui/public/state_management/state_storage/mock.ts
similarity index 57%
rename from src/legacy/ui/public/state_management/state_hashing/get_unhashable_states_provider.ts
rename to src/legacy/ui/public/state_management/state_storage/mock.ts
index 6c43947640ed395..59700cb369e6e8c 100644
--- a/src/legacy/ui/public/state_management/state_hashing/get_unhashable_states_provider.ts
+++ b/src/legacy/ui/public/state_management/state_storage/mock.ts
@@ -17,12 +17,21 @@
  * under the License.
  */
 
-import { AppState } from '../app_state';
-import { GlobalState } from '../global_state';
-import { State } from '../state';
+import { StubBrowserStorage } from 'test_utils/stub_browser_storage';
+import { HashedItemStore } from './hashed_item_store';
 
-export function getUnhashableStatesProvider(getAppState: () => AppState, globalState: GlobalState) {
-  return function getUnhashableStates(): State[] {
-    return [getAppState(), globalState].filter(Boolean);
+/**
+ * Useful for mocking state_storage from jest,
+ *
+ * import { mockSessionStorage } from '../state_storage/mock;
+ *
+ * And all tests in the test file will use HashedItemStoreSingleton
+ * with underlying mockSessionStorage we have access to
+ */
+export const mockSessionStorage = new StubBrowserStorage();
+const mockHashedItemStore = new HashedItemStore(mockSessionStorage);
+jest.mock('../state_storage', () => {
+  return {
+    HashedItemStoreSingleton: mockHashedItemStore,
   };
-}
+});
diff --git a/src/test_utils/public/stub_browser_storage.test.ts b/src/test_utils/public/stub_browser_storage.test.ts
index 7a02221c5205174..26070cde25232f2 100644
--- a/src/test_utils/public/stub_browser_storage.test.ts
+++ b/src/test_utils/public/stub_browser_storage.test.ts
@@ -39,6 +39,18 @@ describe('StubBrowserStorage', () => {
     });
   });
 
+  describe('#clear()', () => {
+    it('clears items', () => {
+      const store = new StubBrowserStorage();
+      store.setItem('1', '1');
+      store.setItem('2', '2');
+      store.clear();
+      expect(store.getItem('1')).toBe(null);
+      expect(store.getItem('2')).toBe(null);
+      expect(store.length).toBe(0);
+    });
+  });
+
   describe('#length', () => {
     it('reports the number of items stored', () => {
       const store = new StubBrowserStorage();
diff --git a/src/test_utils/public/stub_browser_storage.ts b/src/test_utils/public/stub_browser_storage.ts
index aa6820d94381898..b5ee9a24e4c2a00 100644
--- a/src/test_utils/public/stub_browser_storage.ts
+++ b/src/test_utils/public/stub_browser_storage.ts
@@ -17,9 +17,9 @@
  * under the License.
  */
 
-export class StubBrowserStorage {
-  private readonly keys: string[] = [];
-  private readonly values: string[] = [];
+export class StubBrowserStorage implements Storage {
+  private keys: string[] = [];
+  private values: string[] = [];
   private size = 0;
   private sizeLimit = 5000000; // 5mb, minimum browser storage size;
 
@@ -73,6 +73,12 @@ export class StubBrowserStorage {
     this.values.splice(i, 1);
   }
 
+  public clear() {
+    this.size = 0;
+    this.keys = [];
+    this.values = [];
+  }
+
   // -----------------------------------------------------------------------------------------------
   // Test-specific methods.
   // -----------------------------------------------------------------------------------------------
diff --git a/test/functional/apps/home/_navigation.ts b/test/functional/apps/home/_navigation.ts
index 58e0793b2d547f1..96285901289b6ef 100644
--- a/test/functional/apps/home/_navigation.ts
+++ b/test/functional/apps/home/_navigation.ts
@@ -105,7 +105,7 @@ export default function({ getService, getPageObjects }: FtrProviderContext) {
       await browser.get(`${basePath}/app/kibana#/home`, false);
       await retry.waitFor(
         'navigation to home app',
-        async () => (await browser.getCurrentUrl()) === `${basePath}/app/kibana#/home?_g=()`
+        async () => (await browser.getCurrentUrl()) === `${basePath}/app/kibana#/home`
       );
 
       await browser.get(`${basePath}/app/kibana#/home?_g=()&a=b/c`, false);
diff --git a/test/functional/apps/visualize/_area_chart.js b/test/functional/apps/visualize/_area_chart.js
index 47c7a1a6bbee8ca..56f4ded9e02fff2 100644
--- a/test/functional/apps/visualize/_area_chart.js
+++ b/test/functional/apps/visualize/_area_chart.js
@@ -234,7 +234,7 @@ export default function ({ getService, getPageObjects }) {
     describe('embedded mode', () => {
       it('should hide side editor if embed is set to true in url', async () => {
         const url = await browser.getCurrentUrl();
-        const embedUrl = url.split('/visualize/').pop().replace('?_g=', '?embed=true&_g=');
+        const embedUrl = url.split('/visualize/').pop() + '&embed=true';
         await PageObjects.common.navigateToUrl('visualize', embedUrl);
         await PageObjects.header.waitUntilLoadingHasFinished();
         const sideEditorExists = await PageObjects.visualize.getSideEditorExists();
@@ -243,7 +243,7 @@ export default function ({ getService, getPageObjects }) {
 
       after(async () => {
         const url = await browser.getCurrentUrl();
-        const embedUrl = url.split('/visualize/').pop().replace('?embed=true&', '?');
+        const embedUrl = url.split('/visualize/').pop().replace('embed=true', '');
         await PageObjects.common.navigateToUrl('visualize', embedUrl);
       });
     });
diff --git a/src/legacy/ui/public/state_management/state_hashing/index.js b/typings/encode_uri_query.d.ts
similarity index 78%
rename from src/legacy/ui/public/state_management/state_hashing/index.js
rename to typings/encode_uri_query.d.ts
index fe868a9b67bde37..4bfc55462444639 100644
--- a/src/legacy/ui/public/state_management/state_hashing/index.js
+++ b/typings/encode_uri_query.d.ts
@@ -17,7 +17,8 @@
  * under the License.
  */
 
-export { getUnhashableStatesProvider } from './get_unhashable_states_provider';
-export { hashUrl } from './hash_url';
-export { unhashQueryString } from './unhash_query_string';
-export { unhashUrl } from './unhash_url';
+declare module 'encode-uri-query' {
+  function encodeUriQuery(query: string, usePercentageSpace?: boolean): string;
+  // eslint-disable-next-line import/no-default-export
+  export default encodeUriQuery;
+}
diff --git a/typings/rison_node.d.ts b/typings/rison_node.d.ts
new file mode 100644
index 000000000000000..2592c36e8ae9a55
--- /dev/null
+++ b/typings/rison_node.d.ts
@@ -0,0 +1,39 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+declare module 'rison-node' {
+  export type RisonValue = null | boolean | number | string | RisonObject | RisonArray;
+
+  // eslint-disable-next-line @typescript-eslint/no-empty-interface
+  export interface RisonArray extends Array<RisonValue> {}
+
+  export interface RisonObject {
+    [key: string]: RisonValue;
+  }
+
+  export const decode: (input: string) => RisonValue;
+
+  // eslint-disable-next-line @typescript-eslint/camelcase
+  export const decode_object: (input: string) => RisonObject;
+
+  export const encode: <Input extends RisonValue>(input: Input) => string;
+
+  // eslint-disable-next-line @typescript-eslint/camelcase
+  export const encode_object: <Input extends RisonObject>(input: Input) => string;
+}
diff --git a/x-pack/typings/encode_uri_query.d.ts b/x-pack/typings/encode_uri_query.d.ts
new file mode 100644
index 000000000000000..e1ab5f4a70abfe8
--- /dev/null
+++ b/x-pack/typings/encode_uri_query.d.ts
@@ -0,0 +1,11 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+declare module 'encode-uri-query' {
+  function encodeUriQuery(query: string, usePercentageSpace?: boolean): string;
+  // eslint-disable-next-line import/no-default-export
+  export default encodeUriQuery;
+}